(1) Field of the Invention
The present invention relates to novel amino alkane diphosphonic acids and more particularly to novel N-hydroxy alkane amino alkane diphosphonic acids and their alkali metal salts, to a process of making said compounds, to compositions containing them, and to a method of using such compositions.
(2) Description of the Prior Art
Only a limited number of hydroxy amino phosphonic acids are known at present. For instance, German Pat. No. 1,214,229 describes, among others, the production of mono-ethanolamino or, respectively, di-ethanolamino (methyl phosphonic acids). These compounds are produced by phosphono-methylating mono-ethanolamine or, respectively, di-ethanolamine by means of phosphorous acid and formaldehyde. Hydroxy amino (methyl phosphonic acids) in which one or two methylene phosphonic acid groups (--CH.sub.2 PO.sub.3 H.sub.2) are attached to the nitrogen atom, are obtained according to the process of said patent.
German published patent application (Auslegeschrift) No. 2,130,794 relates to a process of producing 1-hydroxy-3-amino propane-1,1-diphosphonic acid by reacting .beta.-alanine with phosphorus trichloride and phosphorous acid. The resulting reaction product is a hydroxy amino diphosphonic acid in which no substituent is attached to the amino group, while the hydroxyl group is attached to the same carbon atom carrying the phosphonic acid groups.